Title :
Output Impedance Shaping for Frequency Compensation of MOS Audio Power Amplifiers
Author :
van der Zee, Ronan ; Mostert, Fred
Author_Institution :
Univ. of Twente, Enschede
fDate :
3/1/2009 12:00:00 AM
Abstract :
A frequency compensation technique for MOS audio power amplifiers is presented that allows the frequency compensation capacitors around the power transistors to be smaller than the circuit parasitics without power or stability penalty. Stability is analysed by inspecting the output impedance of the closed loop amplifier, instead of the traditional open-loop gain. By degenerating the gain of the penultimate stage, the output impedance is shaped such that the stability of the audio amplifier is guaranteed for complex loudspeaker loads. The realized amplifier features a THD of 0.005% @ (1 kHz, 10 W), an SNR of 110 dB(A), and stable operation for any passive load up to 50 nF.
Keywords :
MOS capacitors; audio-frequency amplifiers; circuit stability; compensation; electric impedance; harmonic distortion; power MOSFET; power amplifiers; semiconductor device noise; MOS audio power amplifier; SNR; THD; capacitance 50 nF; circuit parasitics; closed loop amplifier; complex loudspeaker load; frequency 1 kHz; frequency compensation capacitor; output impedance shaping; passive load; penultimate stage gain; power 10 W; power transistors; stability; Circuit stability; Frequency; Impedance; Loudspeakers; MOS capacitors; Operational amplifiers; Power amplifiers; Power capacitors; Power transistors; Stability analysis; Audio amplifiers; Miller compensation; frequency compensation; multistage amplifiers; output impedance; power amplifiers;
Journal_Title :
Solid-State Circuits, IEEE Journal of
DOI :
10.1109/JSSC.2009.2012448
